Tweak docs for log_statement_sample_rate
Author: Justin Pryzby, partly after a suggestion from Masahiko Sawada Discussion: https://postgr.es/m/20190328135918.GA27808@telsasoft.com Discussion: https://postgr.es/m/CAD21AoB9+y8N4+Fan-ne-_7J5yTybPttxeVKfwUocKp4zT1vNQ@mail.gmail.com
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@ -5821,11 +5821,12 @@ local0.* /var/log/postgresql
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Causes the duration of each completed statement to be logged
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Causes the duration of each completed statement to be logged
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if the statement ran for at least the specified number of
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if the statement ran for at least the specified number of
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milliseconds, modulated by <varname>log_statement_sample_rate</varname>.
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milliseconds, modulated by <varname>log_statement_sample_rate</varname>.
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Setting this to zero prints all statement durations. Minus-one (the default)
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Setting this to zero prints all statement durations.
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disables logging statement durations. For example, if you set it to
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<literal>-1</literal> (the default) disables logging statements due to
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<literal>250ms</literal> then all SQL statements that run 250ms or longer
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exceeding duration threshold; for example, if you set it to
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will be logged. Enabling this parameter can be helpful in tracking down
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<literal>250ms</literal>, then all SQL statements that run 250ms or
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unoptimized queries in your applications.
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longer will be logged. Enabling this parameter can be helpful in
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tracking down unoptimized queries in your applications.
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Only superusers can change this setting.
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Only superusers can change this setting.
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</para>
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</para>
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@ -5859,14 +5860,15 @@ local0.* /var/log/postgresql
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</term>
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</term>
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<listitem>
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<listitem>
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<para>
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<para>
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Determines the fraction of the statements that exceed
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Determines the fraction of statements that exceed
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<xref linkend="guc-log-min-duration-statement"/> which to log.
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<xref linkend="guc-log-min-duration-statement"/> to be logged.
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The default is <literal>1</literal>, meaning log to all such
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The default is <literal>1</literal>, meaning log all such
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statements.
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statements.
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Setting this to zero disables logging, same as setting
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Setting this to zero disables logging by duration, same as setting
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<varname>log_min_duration_statement</varname>
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<varname>log_min_duration_statement</varname> to
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to minus-one. <varname>log_statement_sample_rate</varname>
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<literal>-1</literal>.
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is helpful when the traffic is too high to log all queries.
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<varname>log_statement_sample_rate</varname> is helpful when the
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traffic is too high to log all queries.
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</para>
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</para>
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</listitem>
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</listitem>
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</varlistentry>
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</varlistentry>
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@ -6144,7 +6146,7 @@ local0.* /var/log/postgresql
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<note>
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<note>
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<para>
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<para>
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The difference between setting this option and setting
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The difference between enabling <varname>log_duration</varname> and setting
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<xref linkend="guc-log-min-duration-statement"/> to zero is that
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<xref linkend="guc-log-min-duration-statement"/> to zero is that
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exceeding <varname>log_min_duration_statement</varname> forces the text of
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exceeding <varname>log_min_duration_statement</varname> forces the text of
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the query to be logged, but this option doesn't. Thus, if
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the query to be logged, but this option doesn't. Thus, if
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@ -3378,8 +3378,8 @@ static struct config_real ConfigureNamesReal[] =
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{
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{
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{"log_statement_sample_rate", PGC_SUSET, LOGGING_WHEN,
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{"log_statement_sample_rate", PGC_SUSET, LOGGING_WHEN,
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gettext_noop("Fraction of statements over log_min_duration_statement to log."),
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gettext_noop("Fraction of statements exceeding log_min_duration_statement to be logged."),
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gettext_noop("If you only want a sample, use a value between 0 (never "
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gettext_noop("If you only want a sample, use a value between 0.0 (never "
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"log) and 1.0 (always log).")
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"log) and 1.0 (always log).")
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},
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},
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&log_statement_sample_rate,
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&log_statement_sample_rate,
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@ -491,9 +491,9 @@
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# 0 logs all statement, > 0 logs only statements running at
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# 0 logs all statement, > 0 logs only statements running at
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# least this number of milliseconds.
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# least this number of milliseconds.
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#log_statement_sample_rate = 1 # Fraction of logged statements over
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#log_statement_sample_rate = 1.0 # Fraction of logged statements exceeding
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# log_min_duration_statement. 1.0 logs all statements,
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# log_min_duration_statement to be logged.
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# 0 never logs.
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# 1.0 logs all such statements, 0.0 never logs.
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#log_transaction_sample_rate = 0.0 # Fraction of transactions whose statements
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#log_transaction_sample_rate = 0.0 # Fraction of transactions whose statements
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# are logged regardless of their duration. 1.0 logs all
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# are logged regardless of their duration. 1.0 logs all
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